Invasive Species Management

Need noxious weed advice?

We are not able to provide site visits in 2020 but are monitoring calls and questions. See our contact information on the right-hand side of this page.

Protecting natural resources

What We Do

The Jefferson County Invasive Species Management program provides education and outreach to help Jeffco residents learn to identify and manage noxious weeds, forest insect pests and agricultural vertebrate pests.  Our goal is to provide the public with information and offer solutions that they can use to manage their weed and pest problems.

We ensure the compliance with Colorado’s noxious weed, forest pest, and agricultural vertebrate pest regulations on private, county, and state lands.  We also provide technical assistance and support to county departments who are responsible for managing county owned lands.

The program coordinates with private, local, state, and federal agencies to achieve regional pest control.

Who We Are

Our staff includes the Invasive Species Management Coordinator and limited summer help.

Squash bee

Bee of the Month

Each month we will feature a bee profile.  There are 100’s of species of native bees in Jeffco.  Bees support many ecological processes but often go unnoticed.  

Squash bee

Peponapis pruinosa

 By Liam Cullinane, ISM Specialist

Photo Credit: Discoverlife

Squash bee (Peponapis pruinosa) is a solitary bee species that specializes on plants in the Cucurbita genus (squash and gourd plants). Because of this specialization, females only collect pollen from plant species in this genus (summer and winter squashes, pumpkins, gourds, etc.), hence why this bee’s common name is the squash bee. These bees are similar in size to honey bees (although they are a bit larger) and are sometimes misidentified as such.  However, squash bee females nest in the ground in well-drained bare soil and males can often times be found resting in squash flowers. A defining characteristic of this bee species is their foraging behavior, collecting pollen around sunrise, when squash plants open their flowers. This bee species occurs throughout the United States and Mexico and is active in the mid-summer (June-August). 

Weed of the Month

Each month we will feature a noxious weed to help landowners identify weeds they may encounter on their property.

Purple loosestrife

Lythrum salicaria

Purple loosestrife is a List A noxious weed.  It grows as a semi-aquatic perennial forb.  Originally from Eurasia, it was brought to North America as an ornamental but has escaped.   It grows to 6-10 feet tall and can be found along the edges of water bodies, creeks, and rivers.  It is often found growing within cattails and can be hard to spot when new to an area.

The flowers are purple, ¼-½ inch wide, with 5-7 petals in long racemes (flower-heads).  Plants begin to flower in June.  Each plant can produce 2.7 million seeds that may stay viable for 2-3 years.  

Plants have lance-shaped leaves that are about ½ inch wide and 1-3 inches long.  Leaves have distinctive veins parallel to the leaf edge. Stems are 4 to 6-sided, erect, and branch at the ends. Plants may have as many as 30 stems.  Roots are fibrous and extensive.

Purple loosestrife reproduces by seed and plant fragments.  The small seeds can easily be carried by water.  Once established, Purple loosestrife will displace native wetland species and diminish wildlife habitat.


What You Can Do

Garden responsibly. Don’t plant a pest.  

Keep ornamentals contained.

Report sightings of Purple loosestrife to your local weed manager.


The Northwest Invasive Plant Council (NWIPC)

CDA Purple Loosestrife Information

The Nature Conservancy – Element Stewardship Abstract

Invasive Species Compendium

Weed Spotter

The 2020 Weed Spotter program is a citizen science based effort to detect 6 high priority species on Jeffco Open Space parks.  Learn more at our Citizen Science page.


Colorado’s Noxious Weed Awareness Campaign

2020 marks the 30th anniversary of the Noxious Weed Law. Jeffco Invasive Species Management is a partner in Colorado’s Noxious Weed Awareness Campaign.



Jefferson County Open Space will be applying herbicides for noxious weed control at the following parks:

Week of 8/10/2020

  • Alderfer Three Sisters 
  • Apex Park
  • South Table Mountain

Mechanical treatment for noxious weed control at the following parks:

  • Crown Hill Park
  • Meyer Ranch Park
  • Van Bibber Park

Week of 8/17/2020

No herbicide work scheduled for this week

Please Note: dates and locations subject to change.  Always visit the main kiosk at the individual park for current information.